Add workaround function for applying nbfixes

[mattwthompson]

PR Summary:

Implements #267

@zijiewu3 this might be a more formal way of doing what we suggested for your cross-interactions, feel free to give this a shot or suggest any changes

PR Checklist

---

• Includes appropriate unit test(s)
• Appropriate docstring(s) are added/updated
• Code is (approximately) PEP8 compliant
• Issue(s) raised/addressed?

[ahy3nz]

Tests passed locally, code looks good. My only suggestion is checking that a1 and a2 actually get found before calling add_nbxfix?

[codecov]

Codecov Report

Merging #268 into master will increase coverage by 2.91%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #268      +/-   ##
==========================================
+ Coverage   85.76%   88.67%   +2.91%     
==========================================
  Files          10       11       +1     
  Lines        1138     1369     +231     
==========================================
+ Hits          976     1214     +238     
+ Misses        162      155       -7

[zijiewu3]

Thanks. I am going to give it a try.